On the Work of Cartan and Münzner on Isoparametric Hypersurfaces

A hypersurface <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>M</mi><mi>n</mi></msup></semantics></math></inline-formula> in a real space form <inlin...

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Main Authors: Thomas E. Cecil, Patrick J. Ryan
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Axioms
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Online Access:https://www.mdpi.com/2075-1680/14/1/56
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author Thomas E. Cecil
Patrick J. Ryan
author_facet Thomas E. Cecil
Patrick J. Ryan
author_sort Thomas E. Cecil
collection DOAJ
description A hypersurface <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>M</mi><mi>n</mi></msup></semantics></math></inline-formula> in a real space form <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow><mi mathvariant="bold">R</mi></mrow><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>S</mi><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula>, or <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>H</mi><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula> is isoparametric if it has constant principal curvatures. This paper is a survey of the fundamental work of Cartan and Münzner on the theory of isoparametric hypersurfaces in real space forms, in particular, spheres. This work is contained in four papers of Cartan published during the period 1938–1940 and two papers of Münzner that were published in preprint form in the early 1970s and as journal articles in 1980–1981. These papers of Cartan and Münzner have been the foundation of the extensive field of isoparametric hypersurfaces, and they have all been recently translated into English by T. Cecil. The paper concludes with a brief survey of the recently completed classification of isoparametric hypersurfaces in spheres.
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spelling doaj-art-4b4ae7753134412baf81fd751d8642b32025-01-24T13:22:17ZengMDPI AGAxioms2075-16802025-01-011415610.3390/axioms14010056On the Work of Cartan and Münzner on Isoparametric HypersurfacesThomas E. Cecil0Patrick J. Ryan1Department of Mathematics and Computer Science, College of the Holy Cross, Worcester, MA 01610, USADepartment of Mathematics and Statistics, McMaster University, Hamilton, ON L8S4K1, CanadaA hypersurface <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>M</mi><mi>n</mi></msup></semantics></math></inline-formula> in a real space form <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow><mi mathvariant="bold">R</mi></mrow><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>S</mi><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula>, or <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>H</mi><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula> is isoparametric if it has constant principal curvatures. This paper is a survey of the fundamental work of Cartan and Münzner on the theory of isoparametric hypersurfaces in real space forms, in particular, spheres. This work is contained in four papers of Cartan published during the period 1938–1940 and two papers of Münzner that were published in preprint form in the early 1970s and as journal articles in 1980–1981. These papers of Cartan and Münzner have been the foundation of the extensive field of isoparametric hypersurfaces, and they have all been recently translated into English by T. Cecil. The paper concludes with a brief survey of the recently completed classification of isoparametric hypersurfaces in spheres.https://www.mdpi.com/2075-1680/14/1/56isoparametric hypersurfacesDupin hypersurfaces
spellingShingle Thomas E. Cecil
Patrick J. Ryan
On the Work of Cartan and Münzner on Isoparametric Hypersurfaces
Axioms
isoparametric hypersurfaces
Dupin hypersurfaces
title On the Work of Cartan and Münzner on Isoparametric Hypersurfaces
title_full On the Work of Cartan and Münzner on Isoparametric Hypersurfaces
title_fullStr On the Work of Cartan and Münzner on Isoparametric Hypersurfaces
title_full_unstemmed On the Work of Cartan and Münzner on Isoparametric Hypersurfaces
title_short On the Work of Cartan and Münzner on Isoparametric Hypersurfaces
title_sort on the work of cartan and munzner on isoparametric hypersurfaces
topic isoparametric hypersurfaces
Dupin hypersurfaces
url https://www.mdpi.com/2075-1680/14/1/56
work_keys_str_mv AT thomasececil ontheworkofcartanandmunzneronisoparametrichypersurfaces
AT patrickjryan ontheworkofcartanandmunzneronisoparametrichypersurfaces